Issue 196: tQuery and tExpression are not fully extensible

<complexType name="tQuery" mixed="true">
         <sequence>
             <any minOccurs="0"/>
         </sequence>
         <attribute name="queryLanguage" type="anyURI"/>
         <anyAttribute namespace="##other" processContents="lax"/>
     </complexType>
     <complexType name="tExpression" mixed="true">
         <sequence>
             <any minOccurs="0"/>
         </sequence>
         <attribute name="expressionLanguage" type="anyURI"/>
         <anyAttribute namespace="##other" processContents="lax"/>
     </complexType>